The present invention relates to a semiconductor device using a high dielectric constant material.
With miniaturization of semiconductor devices in recent years, it is required that the gate length in transistors be reduced to 0.15 μm and the gate dielectric film thickness to not more than 2 nm when SiO2 is used for such an insulating film. Slimming of the insulating film to a thickness of not more than 2 nm enlarges tunnel current to an unignorable degree.
As a solution to this problem, it has been proposed to use an insulating material with a higher dielectric constant than SiO2 so as to increase the physical film thickness while maintaining the desirable dielectric properties. Among the candidates for the high dielectric constant materials having potentialities to satisfy the above requirements are zirconium oxide and hafnium oxide as described in the February, 2000, issue of NIKKEI MICRODEVICES (pages 93–106).